Storyline 360 Lightbox Close Button

Thank you for this suggestion! It definitely worked, however I noticed a very odd repercussion. As with traditional lightbox functionality (using modern player), the lightbox slides appear as a slightly smaller overlay, with transparent gray background, however as soon as my new custom close button is clicked, the slide size for remaining slides shrinks to the reduced lightbox dimension forever more. It's odd. Does anyone know why that's happening and/or how to remedy? I uploaded screenshots. "Lightbox-1.jpg" shows traditional lightbox appearance (original lightbox close button), where base slide is clearly larger than reduced lightbox slide overlay. "Lightbox-2-AfterCloseBtnClkd.jpg" shows how the project dimension shrinks to the reduced lightbox slide size as soon as the close button is clicked. If you put these 2 screenshots together in photoshop, you can see how the dimension of base layer (and consequently all subsequent slides) has been reduced after closing lightbox slide. If anyone has any advice as to why this is happening and how to fix, I would greatly appreciate your help!

I just noticed something else. Once I click the new custom close button on the lightbox slide, the player controls are all completely disabled for the rest of the course. Can't get into menu, transcript, scrubber, volume, etc. All are disabled.